Hi! A recent bug was solved for builds linked with ld.lld, and tracking it down took way longer than it needed to (a year). Ultimately, it boiled down to differences between ld.bfd and ld.lld's handling of orphan sections. Similarly, the recent FGKASLR series brough up orphan section handling too[2]. In both cases, it would have been nice if the linker was running with --orphan-handling=warn so that surprise sections wouldn't silently get mapped into the kernel image at locations up to the whim of the linker's orphan handling logic. Instead, all desired sections should be explicitly identified in the linker script (to be either kept or discarded) with any orphans throwing a warning. The powerpc architecture actually already does this, so this series seeks to extend this coverage to x86, arm64, and arm. This series depends on tip/x86/boot (where recent .eh_frame fixes[3] landed), and has a minor conflict[4] with the ARM tree (related to the earlier mentioned bug). As it uses refactorings in the asm-generic linker script, and makes changes to kbuild, I think the cleanest place for this series to land would also be through -tip. Once again (like my READ_IMPLIES_EXEC series), I'm looking to get maintainer Acks so this can go all together with the least disruption. Splitting it up by architecture seems needlessly difficult. Thanks! -Kees [1] https://github.com/ClangBuiltLinux/linux/issues/282 [2] https://lore.kernel.org/lkml/202002242122.AA4D1B8@keescook/ [3] https://lore.kernel.org/lkml/158264960194.28353.10560165361470246192.tip-bot2@tip-bot2/ [4] https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8959/1 H.J. Lu (1): Add RUNTIME_DISCARD_EXIT to generic DISCARDS Kees Cook (8): scripts/link-vmlinux.sh: Delay orphan handling warnings until final link vmlinux.lds.h: Add .gnu.version* to DISCARDS x86/build: Warn on orphan section placement x86/boot: Warn on orphan section placement arm64/build: Use common DISCARDS in linker script arm64/build: Warn on orphan section placement arm/build: Warn on orphan section placement arm/boot: Warn on orphan section placement arch/arm/Makefile | 4 ++++ arch/arm/boot/compressed/Makefile | 2 ++ arch/arm/boot/compressed/vmlinux.lds.S | 17 ++++++-------- .../arm/{kernel => include/asm}/vmlinux.lds.h | 22 ++++++++++++++----- arch/arm/kernel/vmlinux-xip.lds.S | 5 ++--- arch/arm/kernel/vmlinux.lds.S | 5 ++--- arch/arm64/Makefile | 4 ++++ arch/arm64/kernel/vmlinux.lds.S | 13 +++++------ arch/x86/Makefile | 4 ++++ arch/x86/boot/compressed/Makefile | 3 ++- arch/x86/boot/compressed/vmlinux.lds.S | 13 +++++++++++ arch/x86/kernel/vmlinux.lds.S | 7 ++++++ include/asm-generic/vmlinux.lds.h | 11 ++++++++-- scripts/link-vmlinux.sh | 6 +++++ 14 files changed, 85 insertions(+), 31 deletions(-) rename arch/arm/{kernel => include/asm}/vmlinux.lds.h (92%) -- 2.20.1
